The electromagnetic actuator disclosed in WO 2011/042472 A1 includes a brushless electric motor, at least two digital Hall effect sensors for detecting the rotation of the rotary drive shaft of the electric motor, electronics for controlling the electric motor in an open-and/or closed-loop manner, and a mechanism for converting the rotation of the rotary drive shaft into linear movement of an adjusting element actuated by the actuator. The electric motor is disposed together with the sensors and the electronics in a common housing.
Such electromagnetic actuator may be utilized in a variety of fields of application to enable reciprocal linear (translational) movement of a machine component connected to a traveling means (e.g., a non-rotating body) of the actuator. In this way, the machine component can be linearly moved in a controlled manner between two defined end positions. So that the desired or necessary end positions of the linear movement are not exceeded, it is known to equip the actuator with end switches that stop the linear movement upon reaching the respective end positions.
However, such end switches involve electro-mechanical components that are disposed, e.g., on the movable traveling means. When the desired maximal traveling range (distance) has been reached, an electromechanical element placed at this location actuates the end switch as soon as it has reached the corresponding maximal position. Then, the current supply to the drive motor is interrupted so that the movement of the traveling means is halted.
In addition or in the alternative, mechanical stops can be mounted at the desired end positions of the traveling movement of the traveling means. In this case, when the traveling means reaches (abuts against) the stop, the current of the drive motor significantly increases. The motor current can be monitored by a controller so that the motor is turned off upon detecting an excessive motor current (i.e. when the motor current exceeds a predetermined threshold).
Such known devices are disadvantageous, because each requires special components to be able to set the defined traveling range limitations of the traveling means. Further, the range limiting means are subject to relatively high mechanical wear which reduces the service life of the actuator.
In addition, it is relatively costly to monitor such known actuators in order to determine when maintenance is required. Devices are known (e.g., “Alimo”—“Actuator Lifetime Monitoring” sold by AB SKF) that can be connected to the actuator in order to read out data concerning the operating time and the load cycles.